In this new project it is planned to develop an experimental design for the concurrent exposure of appropriate biological targets to numerous carcinogens of different classes, each administered at doses which would be expected to produce marginal or undetectable effects in the chosen system. Quantitative exposure/response studies will be addressed to test the hypothesis that many different carcinogens can act synergistically to induce a significant level of carcinogenic response when given concurrently at individually ineffective doses. The methods to be used include in vitro assays for mutagenesis and neoplastic cell transformation and whole animal models. BIBLIOGRAPHIC REFERENCE: Saffiotti, U.: Identifying and defining chemical carcinogens. In Hiatt, H., Watson, J.D., and Winsten, J. (Eds.): Origins of Human Cancer. Cold Spring Harbor Conferences on Cell Proliferation. Cold Spring Harbor Laboratory, N.Y., 1977, Vol. 4, In press.